CN1678960A

CN1678960A - Lithographic method for small line printing

Info

Publication number: CN1678960A
Application number: CNA038203006A
Authority: CN
Inventors: D·范斯蒂恩温克; J·H·拉梅斯
Original assignee: Koninklijke Philips Electronics NV
Current assignee: Koninklijke Philips NV
Priority date: 2002-08-30
Filing date: 2003-08-18
Publication date: 2005-10-05
Also published as: KR20050033078A; WO2004021088A2; JP2005537507A; AU2003255936A1; WO2004021088A3; US20050268804A1; EP1537455A2; AU2003255936A8; TW200415451A

Abstract

The minimal feature width (CD) of a pattern of device features configured in a substrate layer by means of a lithographic process can be reduced considerably, without reducing process latitudes (DOF), by substantially extending the post-exposure bake step and reducing the exposure dose. By the same measures the isofocal CD can be tuned to the design CD so that for an arbitrary CD process latitudes are enlarged.

Description

The photoetching method that is used for little lines printing

The present invention relates to the method that forms the sub-micron width feature pattern in the device substrate layer, the method comprises the following steps:

On substrate, form the resist layer of one of positive corrosion-resisting agent and negative resist type;

Mask is provided, and this mask has corresponding to the mask graph for the treatment of to be formed on the feature pattern in the substrate layer;

Utilization provides the projected bundle of exposure dose, via mask graph irradiation resist layer, distributes thereby produce acid concentration in the resist layer around each imaging features;

In curing after exposure (PEB) step, irradiated resist layer is heated, so that from the highest exposure intensity zone, the positive corrosion-resisting agent layer material becomes solubilized in developer solution, and the negative resist layer becomes and can not dissolve in developer solution;

In developer solution, resist layer is developed,, thereby obtain the resist distribution pattern so that anticorrosive additive material is eliminated from the resist layer zone that solubleness is higher than threshold value; And

Remove material or add material to these zone from the substrate layer zone of being described by the resist distribution pattern, so that in substrate layer, form required feature pattern.

The invention still further relates to this graphic method and make the method for device and the device made from the method.

Utilization is sheltered, material is removed and implantttion technique, and this method can also be used to the manufacturing of the device of integrated circuit (IC) and so on.

Positive type resist layer is understood that it is the resist layer that the zone shone is eliminated in development step.The negative resist layer is understood that it is the resist layer that the zone shone is eliminated in development step.

Substrate is understood that it is for example material of silicon of a slice, and the complete multilayer device such as IC treats to utilize some procedure of processing groups in succession to be fabricated into wherein layer by layer.As main procedure of processing, each these procedure of processing groups comprise: coating radiation-sensitive layer or resist layer on substrate, make substrate and mask registration, the mask graph of this mask is imaged in the resist layer, resist layer is developed, substrate is corroded or inject again and clean via resist layer, and other procedure of processing.Substrate when term substrate has covered different phase in the manufacturing process, that is: do not have or only have the substrate of a device feature layer that has constituted, substrate and all intermediate substrate with except that one deck all device feature layers of having constituted.

The method is used lithographic projection apparatus, and this equipment is the main tool during IC makes.This projector equipment is used to different mask graphs one after the other is imaged on the same location of Semiconductor substrate, and the different aspects place that each mask graph is imaged at substrate is in the different layer.This equipment comprise lighting unit, the mask clamp that is used for holding mask, the substrate clamp that is used for accommodating substrates that is used to provide projected bundle successively and be placed in mask clamp and substrate clamp between optical projection system.Mask is equipped with corresponding to the mask graph for the treatment of to be formed on the device feature figure in this substrate layer, by this specific this substrate layer of mask graph configuration.Can be the optical projection system of the combination of lens combination or level crossing system or these systems, on a resist layer that is applied on the substrate, form the picture of the so-called virtual image of this mask graph.This virtual image has manifested the intensity distributions corresponding to mask graph.

Produce acid in the illuminated zone that promptly is exposed of resist layer, this acid is partly neutralized by quencher.Usually with the baking step to resist layer, this step is called as post exposure bake (PEB) step to step of exposure by thereupon.In positive type resist layer, utilize the hot activation of PEB step to make the acid that stays begin to remove the deliquescent atomic group of the obstruction that is present in the resist polymer chain (solubility-blocking groups).What is called goes to protect the effect of this effect of resist to be, in case go protective effect to occur to a certain degree, promptly reaches a threshold value, and resist just becomes and is dissolvable in water aqueous developer.This means that for the PEB step of length preset time, in virtual image intensity surpasses the zone of given threshold intensity, the resist polymkeric substance will become solubilized.In the negative resist layer, hot activation causes the protection to resist, that is the solubilized resist that is dissolvable in water in the developer solution has become and can not dissolve.

Owing to wish stably to increase the electronic component number in the IC device and the operating rate of this device, be lines or minimum widith that is called critical dimension (CD) and the distance between these features so should stably reduce device feature.Therefore, having the mask graph of distance more and more littler between more and more littler graphic feature and the feature should be by imaging.The resolution characteristic that depends on the lithographic projection apparatus optical projection system is the structure of resolution and mask graph, utilizes this equipment can be with the minimum dimension of desired quality imaging graphic feature.This resolution is proportional to λ/NA, and wherein λ is the wavelength of projected bundle, and NA is the digital ring of optical projection system.Improve digital ring and/or reduce wavelength, can improve resolution.To the increase of sizable digital ring in the current lithographic projection apparatus, be proportional to λ/NA owing to can reduce ²Optical projection system the depth of field and unlikely.And, if digital ring further increased, then revise optical projection system and cross over the aberration in the whole required image visual field and become too difficulty.193nm from extreme ultraviolet (DUV) district used present lithographic projection apparatus is reduced to for example 157nm with wavelength, exist the new problem of the material and the anticorrosive additive material of relevant optical projection system optical element, these materials are enough sensitive to the radiation of this wavelength.For lithographic projection apparatus of future generation, proposed to use wavelength to be about extreme ultraviolet (EUV) radiation of 13nm.Use this radiation really can the more meticulous significantly graphic structure of imaging, have challenge and time-consuming task but the design of EUV projector equipment and exploitation are one.Because EUV is easily by absorption of air, so the path of projected bundle should be in a vacuum, this just has concrete new problem.Suitably and effectively the EUV radiation source is still obtained nowhere, and the radiosensitive new anticorrosive additive material of EUV is awaited exploitation.The EUV lithographic projection apparatus that is suitable for producing IC or other device can not obtain in a few years from now on.

So,, exist very big demand for having significantly less than the conventional projector equipment of employing of the device of the device feature (being lines) of the device of making at present and having the manufacture method of the mask graph of conventional characteristic dimension.In the device substrate layer, constitute the like this little lines of width, also can be called as very little lines (VSL) printing less than 100nm.

For from this very little lines of conventional mask graph printing, exposure dose that is be used for the amount of electromagnetic energy of imaging lines may be enhanced the level of excessive exposure.The effect of overexposure is that the amount of removing the acid molecule that hinders the dissolubility atomic group from the positive corrosion-resisting agent polymer chain increases, and these molecular energies get at the resist zone that reaches near the center of lines to be printed.This center is corresponding to the minimum of intensity in the virtual image that is projected on the resist layer, and this minimum value is corresponding to the black lines of binary mask figure that is black and white pattern.By this way, the resist zone of virtual image below becomes solubilized, causes after the development and corrosion of resist layer, and the device feature that obtains in substrate layer is less than lines corresponding in the virtual image.

But the device widths that utilizes overexposure technology to obtain depends on the focal length variations of optical projection system very much.If projected bundle is focused on the resist layer, the feature that then is projected in the virtual image on this layer has minimum yardstick.If the focal plane of optical projection system is offset with respect to resist layer, then mask graph no longer sharply is imaged on the resist layer, the yardstick of imaging features thereby increase in this resist layer.This means that the maximum intensity in the virtual image that resist layer receives reduces, under the situation that adopts positive corrosion-resisting agent, this causes live width to increase.Second problem that overexposure may occur is that lines are vanished, that is required graphic feature is lines owing to overdevelop and excessive corrosion subsequently disappear.The 3rd problem of overexposure is, the resist on the required resist distribution top incurs loss, and this may cause the undesirable corrosion of required graphic feature.

Utilization to resist layer very off-axis be crooked irradiation (for example well-known bipolar or four utmost points irradiation), or utilize the phase shifting mask figure to replace the binary mask figure, can alleviate above-mentioned each problem.But depend on very much the orientation of graphic feature and the spacing of each feature periodically or in the figure with the picture quality that off-axis illumination obtains.Compare with binary mask, phase shifting mask is very expensive, if treat that the number of the IC that will produce with particular mask is not very big, will be selling at exorbitant prices particularly.

Another problem that various photoetching methods run into is that generally the size of the feature that constitutes in the substrate layer should equal M times of target size, and M is the enlargement factor of optical projection system.Target size is fixed in the IC design, so in mask graph, below be called as the design width.Wherein most important scrambling is the photoetching process scrambling that focal length variations and exposure dose change, and may cause the difference between physical size and the target size.Focal length variations not only can be caused by the imperfection of optical projection system, but also may be due to the virtual image is projected on the resist layer, this virtual image manifest by utilize previous photoetching process below the pattern that causes of the feature pattern that constitutes in the substrate layer.But for every kind of photoetching process, exist specific characteristic dimension, burnt CD such as be called, because they are smaller and can tolerate that bigger focal length and dosage change to the influence of the size of the feature that is configured.These burnt CD depend in used resist and the design configuration consumingly thereby also are neighbour's structures of the feature in the virtual image.Unfortunately, these burnt CD are not equal to the characteristic dimension in the design configuration usually.This means that photoetching process tolerance that is process allowance are very little, thereby must propose very high requirement the depth of field and the exposure dose of optical projection system.

The purpose of this invention is to provide the described method of a kind of beginning paragraph, the method makes it possible to constitute width less than the graphic feature of 100nm and/or have big process tolerance.The method is characterised in that the time span of PEB step and exposure dose are suitable for the design width of feature to be formed.

The present invention is based on and have insight into the parameter that the PEB time span can be used as adjusting process.Except exposure dose, this time length has determined that the acid molecule of maximum illumination region generating can pass resist from minimum irradiation resist zone diffusion reach.So PEB be used to control become solubilized and in development step with the size in the resist zone that is eliminated.This situation is set up positive type resist layer.Under the situation of negative resist layer, the PEB time span is being controlled the solubilized resist becomes insoluble degree.Described seeing clearly can be used to solve above-mentioned each problem.

In an embodiment of the method, in the PEB step, can not dissolve and solubilized between transformation originally have negative slope, the feature of this embodiment is that the PEB time span that increased is used to slope be shifted onto at least 0 slope, and positive slope preferably.

In the photoetching process of using at present, the PEB time span for example was 90 seconds, and the acid concentration in the resist layer distributes and has negative slope, this means can not dissolve and solubilized between transformation have negative slope.For positive corrosion-resisting agent, negative slope means that the desired atop surface area of resist feature of can not dissolving is greater than its bottom section.This resist feature is more unstable less than the resist feature of bottom section than having positive slope that is atop surface area in developing process.For the negative resist feature, negative slope means the atop surface area of desired solubilized resist feature less than its bottom, and this may cause difficulty when removing solubilized resist part.Since the PEB step change acid concentration in the resist layer distribute thereby change can not dissolve and the solubilized anticorrosive additive material between transition position and slope, so the PEB time span can be used as technological parameter, be at least 0 slope and positive slope preferably so that slope changed to from negative slope.

It is the resist layer of 300-350nm that the further feature of the method can be to use thickness.

Have been found that the method and thickness are about 300nm for example for the resist layer of 320-330nm is used in combination, and provide excellent result.

The further feature of the method can be to use a kind of like this resist, and the suitable radiation absorption gradient of this resist is used to reduce the change by the transformation slope between can not dissolving of being caused of the PEB time span that has prolonged and the solubilized anticorrosive additive material.

If for example 90 the degree certain slope be can not dissolve and the solubilized anticorrosive additive material between transformation desired, then can use the method.The slopes of 90 degree mean that separation can not dissolve and the virtual wall of the solubilized anticorrosive additive material surface plane perpendicular to resist layer.For the photoetching process that is designed to obtain with the conventional PEB time in 90 seconds this slope, when adopting longer PEB during the time, slope will change.For example, as the PEB that adopted for 180 seconds during the time, will obtain the positive slopes (for positive corrosion-resisting agent) of 80 degree.This is because exposing radiation is absorbed by resist layer, causes the exposure intensity at place, layer top higher than place, layer bottom.According to the present invention, for positive corrosion-resisting agent, can adopt so-called surface to suppress, so that in place, resist top absorption radiation still less.For negative resist, can adopt the resist surface to strengthen, use developer solution to come resist is developed simultaneously than common higher concentration.

Adopt the longer PEB time may influence the productive rate of photoetching process.Productive rate is understood that the number of the substrate that can process in the unit interval.The time shutter of lithographic projection (exposure) equipment for example was 90 seconds.If as usually in the common process the PEB time also be 90 seconds, the steady flow of substrate from exposure sources to the PEB device that also is called hot plate then can keep exposing.If the PEB time is 260 seconds for example, the substrate that then has been exposed must wait for for 170 seconds before it can be placed in the PEB device, this means that the productive rate of technology is considerably reduced.

According to the present invention, if the further feature of method is that the number of PEB device then can keep high productive rate corresponding to the PEB time span of a substrate and the ratio of time shutter for the substrate to Continuous irradiation carries out the PEB step and uses some PEB devices.

For comprising that the time shutter that substrate is aimed at respect to mask graph is that 90 seconds and PEB time are the given example in 260 seconds, can use 3 PEB devices.For example, if first substrate that exposed is transported to a PEB device, second substrate that exposed is transported to the 2nd PEB device, the 3rd substrate that exposed is transported to the 3rd PEB device, the 4th substrate that exposed is transported to a PEB device, or the like, then can keep original high yield, effectively utilize and cause, promptly be also referred to as the Fab place and exist the hot plate that some do not use simultaneously in IC (device) manufacturing position by the following fact.In this new method, hot plate was used in each partly overlapping time period.

A common problem that runs in the photoetching process is, from having given design CD thereby also being wideer from isolated lines printing with same design CD of the aspect ratio of intensive lines printing of the CD the mask graph.Isolated lines or feature are considered to be in a kind of feature that does not have neighbour's feature in the peripheral region that is about characteristic width dimension.Intensive lines or feature are considered to be in a kind of feature that the mutual distance that is about characteristic width forms the part of series of features.For example, design CD is that the isolated feature of 100nm is printed as the feature that width is 90nm, and the dense feature printed matter has the width of 110nm.For head it off, that is reduce or eliminate the difference of printing width, can utilize equal intensive biasing principle.This principle is based on optical approximate correction (OPC).OPC means that one or more extra features are arranged at the neighbour of design device feature.These extra features are so little, to such an extent as to their not therefore imagings, but certain image that influences the wavefront of the exposing beam part that makes the design feature imaging thereby influence this design feature.Utilize OPC feature specific in the mask graph, can make from dense feature with from the characteristic width that isolates the feature printing to be equal to each other.

But find that the increase of PEB time causes the difference increase between the width of width and the isolated feature of printing of dense feature of printing.For example, if the PEB time was added to for 260 seconds from 90 seconds, then the width of Yin Shua isolated feature is 100nm, and the width of the dense feature of printing is 130nm.OPC feature originally can't be revised the difference of width.

If the further feature of the method is to use the PEB time span estimated to determine the design width of the design configuration of feature as design parameter, then can eliminate this problem in the design phase.

The OPC feature that is used for the correction of print characteristics width can be suitable for the PEB time to be used now, causes and can eliminate width difference once more.Further improvements in methods have been obtained by this way.The also PEB time span that other OPC feature that is used to print the purpose outside the line thickness control might be suitable for selecting.

According to first situation of the present invention, the method is characterised in that the time span of PEB step is increased, so that form the device feature with smallest dimension, this smallest dimension is less than the corresponding smallest dimension of the virtual image of mask graph, and this virtual image is formed in the resist layer by projected bundle.

In this embodiment of method, the PEB time is used as a kind of means of the width of control device feature to be formed, and particularly reduces this width by means of increasing the PEB time.

The further feature of this embodiment is that preferably the PEB step carried out for 140 seconds at least, and less corresponding exposure dose is used to obtain the characteristic width less than 80nm.

Utilize less exposure dose, reduced the quantity of acid molecule, particularly near the minimum strength zone, and reaching the threshold value that influences de-protected this acid molecule quantity of positive corrosion-resisting agent from the bigger distance in minimum strength zone.In this bigger distance, the susceptibility that the focusing of virtual image intensity changes is much lower.The PEB time span from 90 seconds to enlarging markedly of 260 seconds for example more than 140 seconds, also make to be present on a small quantity near the acid molecule in the zone in minimum strength district and can to go protection to resist.So, near the resist of the minimum strength district center solubilized that also becomes, so that reduced the width of graphic feature, although used low exposure dose.The great advantage of the method is that for low exposure dose, the Strength Changes scope that focal length variations causes is much smaller.Because (more effective) of (long) PEB step and acid uses the focus error that projector equipment is caused insensitive, so might print for example wide very little lines of 40nm with bigger process tolerance.

Top situation is effective to positive corrosion-resisting agent.Similar effect appears in the negative resist, and it is protected that condition is that resist becomes, rather than goes protection.

By this way, increased significantly and utilize conventional lithography tool to print the possibility of ever-reduced live width in controlled and reliable mode.

The live width of above-mentioned 40nm is given as the example of possibility live width.The present invention also can be used to print greater than 40nm with less than the live width of the available width of conventional method.The prolongation of PEB time depends on minimum feature to be printed, and live width is big more, and desired prolongation is just more little.The PEB time in described 260 seconds is suitable for printing the wide lines of 40nm highlightedly.In order to print the live width of still very little 40-80nm, can adopt the PEB time span in the 260-140 second still more much bigger than conventional PEB time span.

According to second situation of the present invention, the method is characterised in that, utilizes the adaptive of PEB time span and exposure dose, waits burnt CD to be adjusted to design CD.

By this way, obtained the big process tolerance of the very little and bigger design CD of printing.To wait burnt CD to adjust to design CD and burnt CD such as be considered to not only make equal to design CD, but also the more close design of burnt CD CD such as make.

First embodiment of the method is characterised in that has used the binary mask figure.

Can comprise transparent substrates and for example binary mask of the figure of the chromium feature on the one side, be the most cheap mask type.Utilize this mask of new method combination therewith, can reduce minimum feature significantly, thereby can print and/or can increase significantly the tolerance of typography with this mask.

The feature of second embodiment of the method has been to use the phase shifting mask figure.

Phase shifting mask can be pure phase shifting mask, is also referred to as the few mask of chromium.In this mask, the border of device feature is by the zonule mark of introducing phase shift in projected bundle.Phase shifting mask also can be a kind of like this mask, and wherein, device feature is the feature of opaque for example chromium, and its border is by the phase-shifted region mark.Each phase shift bundle of mask graph partly interferes with each other, thus the characteristics of image that the characteristics of image that forms can access less than the same mask figure from binary mask significantly.Utilize the phase shifting mask of new method combination therewith, can further reduce printable line thickness and/or can increase the tolerance of typography significantly.

The invention still further relates to the method that comprises the device that is distributed in the device feature on the different layers of successively making, the method is used the technology of some structure device feature, and each technology is used for a device layer.The method is characterised in that at least one construction process comprises above-mentioned method.

Because new pattern forming method causes having littler minimum device feature and/or the device of the characteristic dimension determined better, so present invention is also embodied in this device.

From each embodiment that describes below, these and other situation of the present invention is conspicuous, and with reference to each embodiment that describes below, is explained in the mode of non-limitative example.

In the accompanying drawings:

Fig. 1 schematically shows an embodiment of the lithographic projection apparatus that can carry out the method;

Fig. 2 shows the photoetching process of present standard and has wherein adopted the depth of field of technology of the present invention and the relation of CD;

Fig. 3 shows the block scheme of standard photolithography process;

Fig. 4 shows the different virtual image intensity distributions of coke number partially;

Fig. 5 a and 5b show the Bossung curve that utilizes standard technology and wherein adopted the binary mask feature printing that technology of the present invention obtains respectively;

Fig. 6 a and 6b show the Bossung curve that utilizes standard technology and wherein adopted the phase shifting mask feature printing that technology of the present invention obtains respectively; And

How Fig. 7,8,9 burnt CD such as can adjust if showing by means of changing post exposure bake time span and exposure dose.

In the synoptic diagram of Fig. 1, only showing lithographic projection apparatus is the most important module of exposure sources embodiment.This equipment comprises and wherein holds for example projection column of lens optical projection system PL of optical projection system.The mask clamp MH that is used for carrying mask MA is positioned in this system top, and this mask comprises the mask graph C that waits to want imaging.This mask graph is corresponding to the feature pattern for the treatment of to be formed on the feature in substrate layer or the wafer W.Mask clamp constitutes the part of mask platform MT.Substrate platen WT is positioned in the projection column of projection lens system below.Substrate platen is equipped with and is used for for example substrate clamp WH of semiconductor wafer W of clamp substrate.Radiation-sensitive layer PR for example light erosion resistant agent layer is applied on the substrate.Mask graph C should repeatedly be imaged in the resist layer, is imaged among another IC zone or the tube core Wd at every turn.Substrate platen can be moved along X and Y direction, causes after mask graph has been imaged in the IC zone, and next IC zone can be placed under mask graph and the optical projection system.

This equipment also comprises and is equipped with mercury lamp for example or such as illuminator, lens combination LS, reverberator RE and the collecting lens CO of the radiation source LA of the such excimer laser of KrF excimer laser.The projected bundle that is provided by illuminator is that exposing beam PB shines mask graph C.Optical projection system PL is with in the IC zone of this pattern imaging on substrate W.

This equipment also is equipped with some measuring systems.First measuring system is an alignment measurement systems, is used for determining that substrate is with respect to the aligning of mask graph C in the XY plane.Second measuring system is the interferometer system, is used for measuring X and the Y position and the orientation of substrate.Focus error detection system (not shown) also is provided, has been used for determining departing between the focus field of optical projection system or the radiation-sensitive layer PR on image field and the substrate.These measuring systems are parts of servo-drive system, comprise electronic signal process and control circuit and actuator, and the signal that utilizes the enough measuring systems of they energy to present is revised position and the orientation and the focus of substrate.

Aim at detection system and use two alignment mark M1 and M2 in the mask MA, these marks are shown in the upper right portion of Fig. 1.These marks for example are diffraction grating, form but also can for example optically be different from its square or stroke road on every side by other mark.Alignment mark is two dimension preferably, that is extends along two orthogonal direction X among Fig. 1 and Y direction.Substrate W comprises at least two alignment marks, and wherein two P1 and P2 are shown among Fig. 1.These marks are placed in the outside of the area of the image that must form mask graph.Grating mark P1 and P2 be phase grating preferably, and grating mark M1 and M2 amplitude grating preferably.Aiming at detection system can be dual system, and wherein two alignment beams b and b ' are used for surveying substrate mark P2 respectively with respect to the aligning of mask mark M2 and be used for surveying the aligning of substrate mark P1 with respect to mask mark M1.After crossing over the aligning detection system, each alignment beams is incident upon respectively on

radiosensitive detector

3 and 3 '.The bundle that each detector will be correlated with converts electric signal to, and this electric signal is the indication of substrate mark with respect to the degree of registration of mask mark, thereby also is the indication of substrate with respect to the degree of registration of mask.In US-A 4778275, the accurate detection system of a kind of biconjugate has been described, the further details of this system is wherein arranged.

In order accurately to determine the X and the Y position of substrate, lithographic equipment comprises multiaxis interferometer system, schematically shows this system with square frame IF in Fig. 1.In US-A 4251160, describe a kind of twin shaft interferometer system, and in US-A 4737823, described a kind of triaxial interference meter systems.In EP-A 0498499, a kind of five interferometer systems have been described, utilize it can very accurately measure along the displacement of X and Y-axis and around the rotation of Z axle and around the inclination of X and Y-axis.

As shown in Figure 1, the output signal Si of interferometer system and the signal S3 and the S3 ' that aim at detection system are fed to for example microcomputer of signal processing circuit SPU, and this microcomputer is handled these signals, so that the signal Sac of control actuator AC.This actuator moves substrate clamp WH via substrate platen WT along the XY plane.

For example by means of move relative to each other along the Z direction projection lens system and substrate, or by means of the one or more lens elements along Z direction mobile projector system, the output signal of above-mentioned focus error detection system is used to revise focus error.A kind of focus error detection system that can be fixed to projection lens system has been described in US-A 4356392.In US-A 5191200, described a kind of detection system, can survey the local dip of focus error and substrate with it.

For the distance that reduces between details, width and the adjacent devices feature that device feature is lines,, exist the requirement of steady growth so that improve the operating rate of device and/or improve component number in this device.Figure 1 illustrates a tiny degree one example, that can use the details of lithographic projection apparatus imaging in a satisfactory manner, determine by the image quality and the resolution characteristic of optical projection system.By means of increasing digital ring NA and/or reducing the wavelength of projection radiation, having improved resolution characteristic is resolution routinely.Be difficult to expectation in practice and further increase digital ring, and further the reducing and will cause many new problems of projected bundle's wavelength.

The development of the renewal of relevant method of coming the littler graphics details of imaging with the projector equipment that still can make is to adopt stepping and scanning photoetching equipment, rather than the stepping lithographic equipment.In stepping equipment, the full visual field of material illumination, that is whole mask graph is illuminated in an operation, and do on the as a whole IC zone that is imaged at substrate.After an IC zone had been exposed, step proceeded to next IC zone, that is, to place the mode under the mask graph to come mobile substrate clamp in next IC zone.This IC zone is exposed then, or the like, till all IC zones of substrate are provided with mask graph.In step-scan equipment, only rectangle or circular section shape mask pattern zone are illuminated, the subregion of the correspondence in substrate IC zone thereby at every turn be exposed.Under the situation of the enlargement factor of considering optical projection system, mask graph and substrate are moved in synchronization and pass through projected bundle.In a continuous processing, the follow-up subregion of mask graph then is imaged on the corresponding subregion in relevant IC zone at every turn.After being imaged on whole mask graph on the IC area by this way, substrate clamp is carried out step motion, that is begins next IC zone is moved in the projected bundle.Mask then for example is set in its reference position, and then, described next IC zone is scanned exposure.As in the step-scan method, only used the core of image field, thereby only this a part of optical aberration needs to revise, bigger digital ring can be used.By this way, can be reduced to a certain degree with required quality by the width of the device feature of imaging and its spacing.But the density that improves component graphics with optical devices is not enough for follow-on IC and other device.And because the imperfect and photoetching process of the equipment as the optical aberration is imperfect, the set one theory of digital ring, wavelength and scanning theory will not reach actually.

Use can form the optical projection system of the image that is also referred to as the virtual image with very little lines (VSL) in resist layer, can not guarantee that corresponding little device feature just can be formed in the device substrate layer.When forming very little feature in substrate layer, two subject matters appear.That is lines are vanished and the technology focusing changes very high susceptibility.For positive corrosion-resisting agent, it is a kind of like this phenomenon that lines are vanished, and promptly resist is eliminated from the position that it should keep, and causing required feature is that lines disappear.Fig. 2 shows focal variation forms the ability of little lines to photoetching process influence.

Fig. 2 shows the depth of field DOF (unit is a micron) and desired minimal characteristic width (CD: relation critical dimension) of design live width standard technology and 100nm.The situation of the intensive lines of curve C-1 expression, that is lines separate the figure of 140nm from some this lines, and the situation of the isolated lines of curve C-2 expression.This figure and lines are binary mask figures.Binary mask is considered to a kind of mask that comprises transparent substrates, and the one side is equipped with the structure of the zone of opacity of common expression design configuration.Zone of opacity is made up of chromium usually.Inclined to one side coke number scope when the line width variation that the depth of field is considered to obtain remains in design live width ± 10%.As mentioned above and to discuss after a while like that, utilize the overexposure of 100nm live width figure, can print the characteristic width less than 100nm shown in Figure 2.Fig. 2 clearly show that the depth of field is with the reducing and reduce significantly of CD, particularly for intensive lines (curve C-1) all the more so; For the CD of 85nm, DOF is little of 100nm.Difference between the curve C of curve C-1 and isolated lines-2 is formed by isolated lines and a series of lines (intensive) lines that difference between the virtual image intensity distributions partly causes.

Fig. 3 shows the block scheme of photoetching process each step relevant with the present invention.For this figure and following each figure, suppose to use positive corrosion-resisting agent.

Square frame B-1 represents to provide substrate layer with resist layer and substrate is placed the step of the such projector equipment of Fig. 1, treats to form the figure of device feature on this substrate layer.

Square frame B-2 represents to design and provide mask and this mask is placed the step of projector equipment, and this mask comprises the mask graph corresponding to device feature figure to be constituted.

The exposing beam that square frame B-3 represents to utilize provides required exposure dosage shines resist layer via mask graph step.In the exposed portion of resist, utilize the partly quencher of neutralizing acid molecule, acid molecule is separated in a controlled manner.

Square frame B-4 represents to take out the substrate with the resist layer that has exposed and be placed on the stove so that experience the step of post exposure bake in the given time from projector equipment.In positive corrosion-resisting agent, PEB carries out thermal excitation to remaining acid molecule, begins to remove the deliquescent atomic group of the obstruction that is present in the resist polymer chain.This action is promptly so-called goes protection to resist.As a result, to have reached given level be threshold value in case go protection, the resist solubilized that just becomes.A given fixing PEB time span, in order to make the resist solubilized, virtual image intensity must equal threshold intensity at least.

Thereby square frame B-5 represents from PEB device taking-up substrate and is placed on the developer solution so that remove the step that the solubilized part of resist obtains the resist figure.

Square frame B-6 represent from developer solution take out substrate and be placed on corrosion device and/or injection device step.Thereby material is eliminated from the floor district of being described by the resist D graphics that obtains the square frame B-5 and/or adds this floor district to, causes the IC zone that obtains having desirable characteristics.For the manufacturing of complete (IC) device, a series of lithography steps shown in Figure 3 and preparation and intermediate steps are repeated repeatedly, and this number of times equals the number of device substrate layer to be constituted.

In order to constitute width is that device feature below the 100nm is lines, the exposure that can overuse, that is adopt the exposure of the radiation dose that increases.The effect of overexposure is, is also reaching threshold value virtual image intensity near in the resist zone at virtual image minimum of intensity center, and this center is corresponding to the center of lines to be formed.This means resist in these zones solubilized that also becomes, cause after development step,, represent the lines that this is very little with VSL with the resist lines that stay less than virtual image lines.

The very important in practice shortcoming of utilizing overexposure to print VSL is that shown in curve C among Fig. 2-1 and C-2, the live width focusing of printing changes very responsive, and lines are vanished.Observe the behavior of the following virtual image when focus error occurring and just can understand this strong sensitivity that focusing changes.The funtcional relationship of the x position when Fig. 4 shows virtual image intensity I AI (arbitrary unit) with different inclined to one side Jiao (DF) numerical value (the 0-0.6 micron is with 0.1 micron stepping) to the isolated lines of 100nm in the binary mask figure in the resist layer.For each burnt partially numerical value, show separated curve D F1-DF6.Position x=0 is corresponding to the center of minimum of intensity in the virtual image, thereby corresponding to the position at must printing very little lines place.In the area I around the x=0 of position, virtual image intensity sharply increases with burnt partially increase.For the feature that is formed in the substrate layer, this may mean that its width focusing error is very responsive.This situation and lines are vanished and are caused the very little depth of field together.In other words, if adopt overexposure, then exist little processing window and even do not have the processing window for the very little lines of printing.Another shortcoming of overexposure technology is that a large amount of anticorrosive additive materials on the top that resist distributes suffer a loss.

According to the present invention, little exposure dose is used to the VSL printing with long PEB time span.For little exposure dose, near the virtual image minimum of intensity that produces like this thereby be small amount of acid molecule in the area I among Fig. 4, not enough so that the polymer resist solubilized in this zone.Only in away from the area I I of area I, just reach the threshold value that resist is developed.In area I I, virtual image intensity is significantly than more insensitive in area I.If only adopt low exposure dose, then quite wide lines may have been printed.But more efficiently use is by means of prolonging post exposure bake or going to protect the time span of step and realized by the small amount of acid molecule that produces.This makes the acid molecule of equivalent amount can make more polymkeric substance position go protection.Becoming now near the less acid concentration of virtual image minimum of intensity is enough to make the resist solubilized, causes after developing and retains very little resist lines.Because the PEB step that has prolonged and more effective utilization of acid molecule are not subjected to the influence of the focal variation that optical system causes, so obtained the improvement significantly of the depth of field.

The solution that new technology also provides lines to vanish problem.The effect of the PEB time span of using low exposure dose and having prolonged is that slope that resist distributes more just.This inclination is considered to the transition from resist feature (being the top of lines) to its bottom (that is wall of this lines).For the resist lines with positive slope, the top is less than the bottom.This resist lines are more stable and shattered to pieces more insensitive to lines in subsequent process steps.Longer PEB step can also provide the improved cohesive of resist polymkeric substance to device substrate, can prevent that also lines are shattered to pieces.

Littler significantly susceptibility that the novel technique focusing changes (that is bigger DOF) combining with the shattered to pieces chance of lines that has reduced significantly, and the ability that causes printing very little lines significantly strengthens.In Fig. 2, show this point by curve C-3 and C-4.These curves show the relation of the depth of field and desired CD respectively to the identical intensive lines that are used for curve C-1 and C-2 and identical isolated lines.Obviously, new technology makes it possible to print littler significantly CD, and provide for drop to increasing significantly of 50nm and following little CD DOF.

The data of Fig. 2 are from the Bossung curve calculation shown in Fig. 5 a and the 5b.Usually to carry out same characteristic features be the characteristic that lithographic printing technology is described in a series of printings of lines by means of crossing over substrate under the situation that changes exposure dose and focusing in each discrete steps.For example use scanning electron microscope (SEM) to observe the lines of printing, so that obtain focus-exposure matrix (FEM).When the CD numerical value that records is depicted as the function of dosage and focus, just obtain so-called Bossung curve.Fig. 5 a shows the bossung curve that utilizes present standard technology to obtain from the binary mask with 100nm chromium bargraphs of separating 140nm with the PEB time span in 90 seconds.Use thickness to be about 300nm and comprised the resist layer of well-known photoetching resist AR 237 type resists.For 13.80-19.40mJ/cm ²8 different exposure doses in the scope, CD numerical value (unit is nm) are depicted as function (the curve ED of burnt partially numerical value DF (unit is a micron) ₁-ED ₈).It is 80nm that Fig. 5 a shows the minimum line thickness (CD) that can print to represented technological parameter.For this CD, only change of the focus of 200nm that is DOF only are that 200nm can be tolerated.If bigger focus error occurs, the live width that then can't print 80nm.

Fig. 5 b shows from identical binary mask and the Bossung curve that obtains with identical technology, and the littler and PEB time span of different is exposure dose was extended to for 260 seconds significantly.Adopted from 9.40-16.00mJ/cm ²12 different exposure doses (curve ED in the scope ₁₀-ED ₂₁).Fig. 5 b shows in these cases can print the live width of reducing to 40nm, and much bigger focal variation can be tolerated.For the live width of 80nm, the focal variation of 1200nm is tolerable, and for the live width of 45nm, tolerable focal variation is 900nm.

Obtained the raising of new technology, and the situation of the conventional enhancement techniques of the accommodation as bipolar and quadrupole illuminating was not introduced like that to the spacing of feature in the mask graph and the dependence of orientation to minimum CD and focus insensitivity.

If necessary, by means of replacing the binary mask figure with phase shifting mask (PSM) figure, new technology can also make up with the conventional method that improves resolution.In pattern of phase shifts, mark is come by each zone of introducing phase shift in irradiation beam in the boundary line of feature.Be used to interference, can print recently the littler live width of imaging live width from the same characteristic features of binary mask from each bundle part in these zones.Fig. 6 a shows this point, and Fig. 6 a shows and uses 28.00-37.00mJ/cm ²Bossung curve (the curve ED of the pure phase shifting mask lines that 10 different exposure doses in the scope obtain ₃₀-ED ₃₉).CD numerical value is to obtain with the PEB time shutter length of conventional criteria technology with 90 seconds.It is 42nm in principle that Fig. 6 a shows the minimum feature (CD) that can print.But DOF is very little, only 100nm.

If the lower exposure dose and the PEB time span in 260 seconds is used to print same phase shifting mask lines, then obtain the Bossung curve of Fig. 6 b.Fig. 6 b shows CD numerical value (the curve ED that obtains with 6 different exposure doses in the 15.10-18.60 scope ₄₀-ED ₄₅).New technology makes it possible to print the live width of reducing to 36nm now, and for the live width of 37nm, can tolerate the much bigger focal variation until 580nm.

The mask graph that therefrom obtains the Bossung curve of Fig. 6 a and 6b only comprises phase-shifted region.This mask graph is not owing to comprising opaque zone, so be also referred to as the figure of few chromium.New method can also be used to comprise the opaque form that it is characterized by, and settles the mask graph of phase-shifted region on its edge.

Second situation of the present invention relates to the CD that the burnt CD such as grade that technology is determined adapts to the device feature design.Relate to the ability that photoetching process reduces the influence of technological parameter change etc. burnt CD.Seriously influencing most is that change by exposure dose and focal variation causes, from the Bossung curve shown in Fig. 5 a, 5b, 6a, the 6b as seen.But, can tolerate that very large focus and dosage change for the specific characteristic width of burnt CD such as being called as.These burnt CD highly depend on feature in the design configuration around and used resist.Unfortunately, the burnt CD such as grade that determines of technology usually with design hereinafter referred to as design CD in required characteristic width inconsistent.This means that process tolerance is that tolerance is very little usually, make to be very difficult to move rightly photoetching process.

Owing to wait the focal line bar to be decided by the variation that offers the virtual image of resist layer and wherein caused by focal variation to a great extent, old friends can attempt changing or improving this image, so as to reach design CD and etc. the corresponding relation between the burnt CD.But the virtual image is the key link of IC design normally.Only can utilize expensive and inflexible device, for example use phase shifting mask or illumination bipolar and the extreme off-axis that quadrupole illuminating is such, can improve this virtual image by desirable direction.The height as a result of a kind of illumination in back depends on the orientation and the periodicity (spacing) of feature in the mask graph.The another kind that burnt CD such as makes to equal to design CD is selected to be to use another kind of anticorrosive additive material.But this may be with focal line bars such as uncontrollable mode skews.Because the change of anticorrosive additive material also has influence on the others of photoetching process, so this is not a kind of solution of reality.

The present invention utilizes such fact, promptly in the PEB of positive corrosion-resisting agent step, acid molecule is diffused into the zone that receives minimum strength by the resist polymkeric substance from the zone that receives maximum virtual image intensity, reach design CD and etc. the corresponding relation between the burnt CD.As a result, distribute in the acid concentration of carrying out obtaining after the PEB step and just be different from the acid concentration that former cause virtual image intensity distributions determines and distribute.The PEB step also affects relevant with virtual image feature different acid concentration and distributes, and this different distribution may be from the various focal positions of the virtual image, thereby is offset the infall of these distributions.For example because the major part of acid molecule diffuses out acid concentration distribution place of present slope maximum, the position at place will change so different focus lines intersect each other.The skew of intersection location such as means at the skew of focal line.The present invention utilizes the PEB time span to adjust sour range of scatter, distributes and adjusts and intersect burnt CD such as relevant therewith thereby control final acid concentration.With the long PEB time, diffusion occurs in the long scope, and final acid distributes thereby is different from the distribution that obtains with the short PEB time.

Because the PEB time span has determined how be used to make the de-protected efficient of resist polymkeric substance by the acid molecule that the virtual image of resist exposure is produced, so the anticorrosive additive material that exposure dose should be suitable for avoiding too many is gone to protect and be eliminated in development step.Because it is that the how near resist in center of feature becomes and protects thereby solubilized that PEB time span and exposure dose have determined from the resist lines, so these parameters such as are controlling at burnt CD.

Fig. 7-9 comes into plain view the effect of adjusting PEB time span and exposure dose simultaneously.Fig. 7 shows and utilizes present standard technology, with the PEB time span in 90 seconds, separates the Bossung curve that the intensive lines of the 100nm chromium bargraphs of 140nm obtain from binary mask.Exposure dose with for used identical of the curve that obtains Fig. 5 a, cause the curve of the curve of Fig. 7 similar in appearance to Fig. 5 a.Fig. 7 shows the Bossung curve (ED of the match of each exposure dose ₁-ED ₈), rather than the lines of the measurement CD numerical value of connection layout 5a burnt CD such as are on which kind of degree so that point out to belong to the CD numerical value of given exposure dose.The curvature of these curves is more little, for all CD of relevant exposure dose, with regard to burnt situation such as approaching more grade.For the process conditions of Fig. 7, wait burnt CD to be positioned at around the design CD of 100nm.Thick straight line BL1, BL2 represent the border of the CD numerical value still tolerated.Usually, these lines are placed in design CD numerical value+10% and-10% place.

Fig. 8 show utilization except the PEB time span be shortened 30 seconds and exposure dose be increased the Bossung curve that obtains from identical binary mask of other all identical technology.Adopted 32.00-44.00mJ/cm ²7 different exposure doses (curve ED in the scope ₅₀-ED ₅₆).For the process conditions of Fig. 8, wait burnt CD to be positioned at about 130nm; 32.00mJ/cm ²The curve ED of exposure dose ₅₀Demonstrate minimum curvature.These conditions thereby be not suitable for printing the design CD that is about 100nm between the boundary line at 90nm and 110nm place respectively, but be very suitable for printing the design CD that is about 130nm between the boundary line that is displaced to 120nm and 140nm respectively.For the higher exposure dose of Fig. 8, before acid molecule began to spread significantly, quencher was buried in oblivion fully.

Fig. 9 shows and Fig. 7,8 and the Bossung curve of the used identical binary mask of Fig. 5 b.Used now significant prolongation the PEB time span in 260 seconds, this and used identical of the Bossung curve that obtains Fig. 5 b.And the exposure dose of Fig. 9 is identical with Fig. 5 b's, causes two to illustrate similar Bossung curve.In Fig. 9,13.60mJ/cm ²The curve ED of exposure dose ₁₇Demonstrate minimum curvature, cause the process conditions of representing for this figure, wait burnt CD to be positioned at about 60nm.Fig. 9 also demonstrates for the PEB time span that has prolonged significantly, and the CD numerical value of the broad range between the 50-90nm is that standard etc. is burnt, this means for the curvature of the Bossung curve of these CD numerical value with etc. the difference of burnt CD be less.This means that utilize very simply prolonging of PEB step, it is more insensitive to the focal variation of feature patterns different on the substrate (wafer) that photoetching process generally becomes on a large scale.In addition, therefore the orientation of feature and periodically irrelevant can be used to various purposes in new technology and the figure.For the low exposure dose of Fig. 9, quencher all exists in whole PEB step.

The present invention has been in having provided a kind of method, makes it possible to burnt CD such as mode adjustment independently and need not change the virtual image.The method can easily realize and provide huge advantage in the photoetching process at present.The method make it possible to etc. burnt CD be adjusted to corresponding to the design CD.This means and enlarged the purposes scope that given resist can be used significantly.The ability of burnt CD such as adjustment provides the maximum possible process window (process tolerance) of possibility under any circumstance use to(for) graphic structure to be printed.The method can also be used to technology is adjusted to the combination property of the maximum with the device feature of printing different size simultaneously.

Utilize positive corrosion-resisting agent to describe the present invention, but also can be applied to adopting in the photoetching process of negative resist.To in negative resist, produce similar effect according to various measures of the present invention, yet even be the also soluble resist of resist protection become insoluble machine-processed aspect, rather than go aspect the protection mechanism at resist.

The slope that the present invention can also be used to dissolve the transformation between anticorrosive additive material and the solubilized anticorrosive additive material changes at least 0 slope and positive slope preferably from negative slope.

In the PEB time span is in the photoetching process of for example present use in 90 seconds, and acid concentration in the resist layer distributes can have negative slope, this means can not dissolve and the solubilized anticorrosive additive material between transformation can have negative slope.For positive corrosion-resisting agent, negative slope means that the desired top surface district of resist feature of can not dissolving is greater than its bottom zone.This resist feature is more unstable than the resist feature with positive slope (that is the top surface district that has is less than its bottom zone) in development step.For the negative resist feature, negative slope means the top surface district of desired solubilized resist feature less than its bottom zone, and this can cause difficulty when removing solubilized resist part.Because the acid concentration that the PEB step has changed in the resist layer distributes, thus change can not dissolve and the solubilized anticorrosive additive material between the position and the slope that change, change slope so the PEB time span can be used as technological parameter.

Utilize thickness to be about the resist layer of 300nm, obtained the result shown in Fig. 2,5b, the 6b, 7,8,9.This shows the resist thickness that is very suitable for this routine.Thereby the present invention can be used to conventional photoetching process situation.

If adopt the long PEB time according to the present invention, then can change can not dissolve and the solubilized anticorrosive additive material between the amplitude of transformation slope.With the PEB time be for example slopes of 90 degree that the common process in 90 seconds obtains, if the PEB time was lengthened to for 180 seconds, then can change over for example slopes of 80 degree.The slopes of 90 degree mean that separation can not dissolve and the virtual wall of the solubilized anticorrosive additive material surface plane perpendicular to resist layer.The change of slope magnitude absorbs exposing radiation by resist layer and causes, and this absorption causes the intensity of layer exposure intensity at place, top greater than place, layer bottom.The PEB time that has prolonged can cause in positive corrosion-resisting agent that slope magnitude becomes too little, and can cause that in negative resist the negative slope amplitude becomes too big.In order to offset the absorption that changes on the resist thickness, can take the following slope problem measure different with negative resist to positive corrosion-resisting agent.For positive corrosion-resisting agent, can use so-called surface to suppress, it means that locating less radiation at the top of resist layer is absorbed.For the negative resist surface, utilize the resist that common process is manifested positive slope, can solve the slope problem, this utilizes strong surface to strengthen the rate of dissolution that has the developer solution of higher concentration of developer to improve in the development step with closet and obtains.For development step, the technology of positive corrosion-resisting agent and negative resist is symmetry no longer; For negative resist, adopt the higher developer of concentration to avoid negative slope.Utilize above-mentioned extra measure, method of the present invention is improved.

Can influence the productive rate of photoetching process with the long PEB time.Productive rate is considered to the number of substrate that can be processed in the unit interval.The time shutter of lithographic projection (exposure) equipment is 90 seconds for example.If as usually in the common process the PEB time also be 90 seconds, the substrate that then can keep exposing stably flows to the PEB device that is also referred to as hot plate from exposure sources.If the PEB time is 260 seconds for example, the substrate that then has been exposed must wait for for 170 seconds before can being placed in the PEB device, this means that the productive rate of technology has been considerably reduced.

Utilization can keep the high yield of technology corresponding to the PEB time span of a substrate and some PEB devices of the ratio of time shutter.For comprising that the time shutter that substrate is aimed at respect to mask graph is that 90 seconds and PEB time are the given example in 260 seconds, will adopt 3 PEB devices.If first substrate that exposed is transported to a PEB device, second substrate that exposed is transported to the 2nd PEB device, the 3rd substrate that exposed is transported to the 3rd PEB device, the 4th substrate that exposed is transported to a PEB device, or the like, then can keep original high yield, effectively use the following fact to cause, promptly make the position and exist some hot plates that are not used simultaneously being also referred to as the IC of Fab (device).

A common problem that runs in the photoetching process is, from having given design CD thereby also being that the aspect ratio of intensive lines printing of the CD the mask graph is wideer from the feature of isolated lines printing with identical design CD.Isolated lines are feature is considered to be in does not have neighbour's feature in the peripheral region of characteristic width magnitude size a kind of feature.Intensive lines or feature are considered to form with the phase mutual edge distance of characteristic width magnitude a kind of feature of the part of series of features.For example, design CD is that the isolated feature of 100nm is printed as the feature that width is 90nm, and dense feature has the width of 110nm.For head it off, that is reduce or eliminate the difference of printing width, can utilize equal intensive biasing principle.This principle is based on optical approximate correction (OPC).OPC means that one or more extra features are arranged at the neighbour of design device feature.These extra features are so little, to such an extent as to their not therefore imagings, but certain image that influences the wavefront of the exposing beam part that makes the design feature imaging thereby influence design feature.Utilize OPC feature specific in the mask graph, can make from dense feature with from the characteristic width that isolates the feature printing to be equal to each other.

According to the present invention,, then can eliminate this problem if the PEB time span of estimating is used as the design width that design parameter is determined the design configuration of feature in the design phase.

The OPC feature of the characteristic width correction that is used to print can be suitable for the PEB time to be used now, so that can eliminate width difference once more.By this way, further improvements in methods have been obtained.The PEB time span that other OPC feature of other purpose outside also the line thickness that is used to print might being controlled be suitable for selecting.

In above-mentioned explanation, advised that the feature of printing can have the width identical with individual features in the mask graph.This means that optical projection system is 1: 1 a imaging system.Lithographic projection apparatus has for example 1/4 or 1/5 enlargement factor usually, and the width that this means mask features is 4 or 5 times of width of the feature of printing.As far as possible simply and not consider the enlargement factor of optical projection system in order to make explanation.

The objective of the invention is to improve the method that device is successively made, this device comprises the device feature that is distributed on the different aspects, and the method adopts some technologies that constitute device feature, the corresponding device aspect of each technology.Realize the present invention by means of constituting in the technology at least one, the present invention also is embodied in the method.

New pattern forming method as causing having littler minimum device feature and/or more definite characteristic dimension present invention is also embodied in this device.

Though utilize concrete lithographic projection apparatus and utilize the manufacturing of IC to describe the present invention, the present invention is not limited to this.The present invention can also be used in other device manufacturing of picture crystal slab (crystalpanel), thin-film head, integrated planar optical system etc.And the present invention can be used in combination with any projector equipment that can form the required virtual image.

Claims

1. method that forms the feature pattern of sub-micron width in the device substrate layer, the method comprises the following steps:

Utilization provides the projected bundle of exposure dose, via mask graph irradiation resist layer, distributes thereby produce acid concentration in the resist layer around the feature of each imaging;

In curing after exposure (PEB) step, irradiated resist layer is heated, so that from the highest exposure intensity zone, the material of positive type resist layer becomes solubilized in developer solution, and the material of negative resist layer becomes and can not dissolve in developer solution;

In developer solution, resist layer is developed,, thereby obtain the resist distribution pattern so that anticorrosive additive material is eliminated from the resist layer zone that solubleness is higher than threshold value;

Remove material or add material to this zone from the substrate layer zone of being described by the resist distribution pattern, so that in substrate layer, form required feature pattern, it is characterized in that the time span of PEB step and exposure dose are suitable for the design width of feature to be formed.

2. the described method of claim 1, wherein in the PEB step, can not dissolve and the solubilized anticorrosive additive material between transformation originally have negative slope, the PEB time span that it is characterized in that increasing is used to slope be shifted onto at least 0 slope, and positive slope preferably.

3. claim 1 or 2 described methods, it is characterized in that adopting thickness is the resist layer of 300-350nm scope.

4. claim 1 or 3 described methods is characterized in that, adopt to have the resist of suitable radiation absorption gradient, so that reduce variation by the slope of the transformation between can not dissolving of being caused of the PEB time span that prolongs and the solubilized anticorrosive additive material.

5. claim 1,2,3 or 4 described methods, utilize same photolithographic exposure system, so that in the substrate layer of substrate in batch, form same figure in succession with same mask graph, it is characterized in that, a plurality of PEB devices are used to the substrate that exposed is in succession carried out the PEB step, and the number of PEB device corresponds essentially to the PEB time span that is used for a substrate and the ratio of time shutter.

6. any one described method among the claim 1-5, wherein, provide the step of mask graph to comprise the figure that design has optical approximate correction feature, it is characterized in that, in the design phase, the PEB time span of expectation is used as the design width that design parameter is determined the characteristic Design figure.

7. any one described method among the claim 1-6, it is characterized in that the time span of PEB step is increased, so that form device feature with smallest dimension, this smallest dimension is less than the corresponding scale in the virtual image of mask graph, and this virtual image is projected bundle and is formed in the resist layer.

8. the described method of claim 7 is characterized in that, the PEB step was performed at least 140 seconds, and corresponding less exposure dose is used to obtain the characteristic width less than 80nm.

9. any one described method among the claim 1-6 is used to the photoetching process of burnt CD such as having, it is characterized in that, by adaptive PEB time span and exposure dose, will wait burnt CD to adjust to design CD.

10. any one described method among the claim 1-9 is characterized in that using the binary mask figure.

11. any one described method is characterized in that using the phase shifting mask figure among the claim 1-9.

12. method of successively making device, this device comprises the device feature that is distributed on the different aspects, the method adopts a plurality of technologies that constitute device feature, each technology is used for a device aspect, it is characterized in that at least one constitutes technology and comprises any one described method among the claim 1-11.

13. one kind is utilized the device that any one described method is made among the claim 1-12.